“This study examined the effect of an acute bout of submaximal non-fatiguing inspiratory loading on maximal inspiratory pressure (MIP), and on the activation of the diaphragm and intercostals using surface electromyography (sEMG).”

Conclusion:

“The significant increase in MIP and intercostal root mean square amplitude after inspiratory loading suggests that MIP efforts were initially submaximal, and that prior loading enabled full activation. The changes in diaphragm and intercostal root mean square amplitude may also reflect an improvement in the synergy between them during these maximal efforts.”